本論文主要目的，由正交分頻多重接取系統(Orthogonal Frequency Division Multiple Access,OFDMA)所演變至今的單載波分頻多重存取(Single carrier frequency division multiple access, SC-FDMA )系統技術中的區域式分頻多重存取(L-FDMA)載波映射系統，進行峰值對平均功率比(PAPR)降低及比較。所採用是截波(Clipping)技術[7]及擴壓(Companding)技術[8]，並且於IEEE 802.16所提出之SUI(Stanford University Interim)通道模型的中的SUI-3通道模型與另一個國際電信聯盟無線電通信組(ITU)無線通道中的低速通道(Pedestrian A)與高速通道(Vehicular A)進行通道模擬，確認峰值對平均功率比(PAPR)降低後的BER(Bit Error Rate)效能影響狀況。由模擬結果指出，於LFDMA系統下分別僅單獨加入截波技術與擴壓技術後，PAPR僅有降低約1dB左右。但結合兩者技術後，於QPSK調變下的模擬結果，PAPR約可降低至4.8dB，較原系統的7.5dB的PAPR還低約2.7dB左右。而在16QAM的調變下，PAPR約可降低至5.1dB，較原系統的8.2dB的PAPR還低約3.1dB左右。進而比較於OFDMA系統使用QPSK調變系統下，可降低至6dB左右的PAPR，較原系統的10.2dB的PAPR還低約4.2dB。且於各個通道效能模擬表現下，加入PAPR降低的技術後，可擁有與原系統類似的BER，並不會造成原系統效能大幅降低。 ;The main purpose of this thesis is to investigate the PAPR reduction comparison for the evolved localized (LFDMA) subcarrier mapping of the OFDMA technology, SC-FDMA. Clipping and Companding are used as the PAPR reduction technique. The channel models used in the simulation are SUI-3 channel model of IEEE 802.16 SUI proposed along with the ITU channel models in the low-speed channel(Pedestrian A) and high-speed channel (Vehicular A). The simulation are conducted to reveal BER performance under the conditions with the PAPR reduction techniques. As indicated by the simulation results, under the LFDMA systems, there is about 1 dB PAPR reduction by using either Clipping technology or Companding technology separately. If the combination of the two technologies is employed, PAPR can be reduced to be approximately 4.8dB in the simulation under QPSK modulation. Compared with the PAPR of the original system(7.5dB), it is reduced by about 2.7dB. In the 16QAM modulation under, PAPR can be reduced to be about 5.1dB. Compared with the original system (8.2dB), it is reduced by about 3.1dB. Then, we make comparison in OFDMA systems by using QPSK modulation, PAPR can be reduced to be about 6dB. Compared with the original system(10.2dB), it is reduced by about 4.2dB. As revealed in the performance curves, adding PAPR reduction techniques have the similar BERs of the original systems, and will not cause significant reduction of the original system performance.
